What's so bad about having a favorite child?

Jill Smokler loves her three children equally, but that doesn't mean she doesn't have a favorite.

At any given moment, she says, one of her little darlings is bound to be a little more likable than the others.

"Whenever I've had an infant, that one has been the favorite for several months because they're so sweet and they're so precious and they're not talking back or getting into things they shouldn't," says Smokler, a mommy blogger (scarymommy.com) and author of "Motherhood Comes Naturally (and Other Vicious Lies)" (Gallery Books).

"Sometimes the dog is my favorite child — not often, but sometimes she is."

Parental favoritism has gotten a fresh look in the past few years, with books such as "The Favorite Child" by Ellen Weber Libby, blog posts ("Admit it, you have a favorite kid. I do," at Babble.com), a reality show ("Keeping Up With the Kardashians") and even TV commercials tackling the once-taboo topic. In a recent TV ad for Cars.com (slogan: "Hate drama? Go to Cars.com"), parents create unnecessary drama by telling their petulant post-adolescent daughter, "Actually, we love your brother more than you."

Instead of denying uncomfortable feelings or hiding behind parenting platitudes, the new voices on the issue are offering a matter-of-fact and at times irreverent take on parental bias. The point isn't that having a passing preference is good or bad; it's that it's human and can be dealt with in constructive ways.

Research indicates that one-third to two-thirds of parents favor one or more children, and some informal estimates are much higher.

Asked how common it is for a parent to have a favorite, Libby, a psychologist in Washington, D.C., laughs: "Universally."

"The problem is not that parents have a favorite," Libby adds. "The problem is often when parents deny it because that makes everyone a little crazy. The second problem is when people hear the word 'favorite,' and they get a little nervous and defensive. Favoritism doesn't have to be bad. It's what we do with it that makes it disastrous or productive."

The upside of having a favorite is that the child grows up feeling more confident, Libby says. But she cautions against singling out kids for special treatment, such as fewer chores or more lenient punishments, which can make them feel like they're above the rules. Similarly, poorly handled favoritism can make it hard for a child to separate from a parent and develop his own independent identity, Libby says. Favoritism can cause problems in the child's adult relationships, because spouses and partners can't provide the same kind of off-the-charts affirmation as a doting parent.

Research over several decades has linked parental favoritism (often defined as unequal treatment) to negative outcomes in childhood, including lower self-esteem and higher anxiety, according to a 2010 article in the Journal of Marriage and Family, co-authored by Purdue University sociology professor J. Jill Suitor. Interestingly, the article cites evidence that favoritism itself is more strongly linked to a child's psychological well-being than whether the individual child was favored or unfavored.

Suitor, who with Karl Pillemer of Cornell University and Megan Gilligan of Purdue, has studied the effects of parental favoritism in later life, says that parents of young children probably can't avoid having preferences among their kids. But she says that making those feelings obvious can have a negative long-term effect on sibling bonds.

"We do know that perceptions of favoritism do seem to have a detrimental effect" on relationships among adult siblings, Suitor says. "There clearly is a measurable increase in tension and decrease in closeness."

Ideally, Libby says, favorite-child status will rotate among children, creating a fluid system in which parental preferences change according to factors such as the children's ages, interests and interactions with their parents. That way, she says, each child gets the benefit of parental recognition, and no one gets overindulged.

The favorite-child issue has been explored on "Keeping up With the Kardashians," with Kris Jenner's older children complaining that her look-a-like daughter Kim Kardashian is her favorite.

And last year Canadian radio host Buzz Bishop landed on "Good Morning America" due to a controversial blog post in which he said he loved both his sons equally, but preferred older children in general and his older son in particular. Bishop was blasted online, in part for going public with his preference, which readers thought might eventually be hurtful to his younger son.

But many readers agreed with Bishop's basic message: Deep down, many parents have these feelings.

"It's OK for us to internally have a favorite, and perhaps to externally write about it on the Internet," Bishop says.

"But to externally treat your children differently — that's where you're going to have problems. When it comes to encouraging and nurturing them, you have to give each of them equal opportunity."

Smokler says she has different feelings toward a child who is going through an affectionate stage and one who is going through a difficult one, but she's careful not to treat one better than the other. She tries to be aware of her own behavior and finds it helpful to spend "alone time" with all of her kids, giving each one some undivided attention.

Right now, she says, one of her children is definitely "the least likely to drive me to drink at 4 p.m.," but she fully expects that her preference will change.

"The tides will turn and they'll turn back," she says. "And that's the way it will always be."